Engineering Commons^™

Photolithographic Fabrication Of 3d Penrose-Like Quasi-Photonic Crystal Polymeric Templates Utilizing Lab-Made Phasemask, Faraon Torres-Lazos

Theses and Dissertations - UTB/UTPA

Photonic crystals (PhC) have recently become of great interest because of their potential as replacement of electronics and/or supplement to semiconductors technology. The PhC’s capability to make compact integrated optical circuits has already made possible the laboratory manufacture of an array of different types of optical waveguides, cavities and filters. The work presented here aimed to simultaneously fabricate a 3D-PhC templates employing six-beam holographic lithography. The basic procedures included recording gratings using interference field of laser sources in a photoresist coating on a glass substrate. The manufacturing method utilized only one optical element, a phasemask, drastically reducing the complexity of …

Photonic Crystal Design And Fabrication Assisted By Tunable Femtosecond Oscillator Laser, Kristofer B. Ohlinger

Theses and Dissertations - UTB/UTPA

Photonic Crystals have the potential for engineered light interaction as directed by the photonic bandgap, a property that details the prohibited propagation region and ultimately the ability to guide light. A so called, photonics-on-chip, would incorporate arbitrary light guiding with functional elements in one package. The realization of such a device is subject to the fabrication paradigms implemented and this thesis is concerned with holographic lithography as a means for creating polymer photonics crystal templates and two-photon polymerization for incorporating light guiding pathways.

In this thesis, the design of the to-be-fabricated structures has been co-opted by computational exploration of the …

On Nonlinear Response Of Micro And Nano Capacitive Resonators, Martin William Knecht

Theses and Dissertations - UTB/UTPA

The nonlinear response of an electrostatically actuated micro/nano-resonator is investigated. The resonator is parametrically actuated using an electrostatic force with a first order fringe correction. Viscous damping and the Casimir effect are included. The resonator is studied using the Method of Multiple Scales in a direct approach of the problem and then compared numerically using a Reduced Order Model based on the application of a Galerkin procedure. In addition to primary resonance (ω0), parametric resonances are found at half (½ω0), twice (2ω 0), and three-halves ([special characters omitted]ω0) natural frequency. The frequency response is investigated for excitations near primary and …

Hardware Microkernels - A Novel Method For Constructing Operating Systems For Heterogeneous Multi-Core Platforms, Jason M. Agron

Graduate Theses and Dissertations

Today's standard operating systems (OSes) do not have the proper structure, nor support for executing on heterogeneous multi- and many-core platforms. These deficiencies manifest in symptomatic issues that range from relatively low-level application binary interface (ABI) compatibility problems, to higher-level concerns such as application programmer interface (API) compatibility, synchronization, and caching issues. These issues in turn reflect back up to the programmer through a lack of a standard set of OS services. Non-uniformities in the hardware architecture are also reflected back into the programming model. In total these issues combined break down the most fundamental benefit of modern operating systems; …

Design And Testing Of Orifice Valves For Use In Freight Railcars Hydraulic Suspension System, Awni K. Alshakhshir

Theses and Dissertations - UTB/UTPA

The work presented in this thesis describes the specific steps undertaken to design and test two spool type control valves that will be part of Amsted Rail’s innovative vertical hydraulic damper system. The design challenge lies in the requirement that these spool valves must maintain a linear relation between pressure drop, flow rate, and position, during the extension and retraction cycles of the hydraulic damper. To this end, a series of laboratory experiments were conducted on spools having different land geometries in order to acquire the optimum apertures that will produce the desired performance based on simulation data provided by …

Electrorheological Fluid Effect Of Polymer Coated Carbon Nanofibers And/Or Fullerenes In Liquid Crystals, Steven S. French

Theses and Dissertations - UTB/UTPA

An ER fluid is a ‘smart’ visco-elastic material, with flow properties influenced by external electric fields, whereby its viscosity increases within the field and returns to its inherent viscosity without the field present. This unique behavior opens many possibilities for new technologies. The optimization of ER fluid performance depends on the chemical and structural compositions of the particles in suspension and the suspension itself. Recent inclusion of nano-particles within ER fluids has shown a relationship to favorable ER trends. Therefore, this research involved nano-laden ER fluid samples of fullerenes (C60) and/or polymer coated carbon nano-fibers as the dispersed phases. These …

An Analytic Hierarchy Process Approach To Assess Health Service Quality, Yan Li

Theses and Dissertations - UTB/UTPA

While improving quality in health care is currently at the forefront of professional, political, and managerial attention, the key dimensions constituting health-care quality have not been fully understood. Also, few valid approaches have been proposed to the measurement of health-care quality. In this research, the Analytic Hierarchy Process (AHP) approach is applied to study the structure of health-care quality and deducted relative importance weights for each of the quality elements. A statistical quality model is derived to assess medical equipment quality which is an important part constituting the general health-care quality. Finally, the application of the AHP model to assess …

A Stochastic Product Priority Optimization Method For Remanufacturing System Based On Genetic Algorithm, Xiong Xiong

Theses and Dissertations - UTB/UTPA

Increasing number of manufacturers are developing remanufacturing facilities to recover end-of-life products for product/component reuse and material recycling while the high uncertainty pattern of returned products complicates the production planning. In this thesis a stochastic production priority optimization method, considering various priority concerns for remanufacturing systems is developed. Priority ranking and matching algorithm is developed to determine the priority rule, using thirteen weighting factors. Queueing models are developed to formulate the objective function, a genetic algorithm is then developed to search optimal solution under different business configurations. Result of this research will provide insights to priority assignment mechanism, which in …

Security Vulnerability Evaluation Of Popular Personal Firewalls And Operating Systems, Sirisha Surisetty

Theses and Dissertations - UTB/UTPA

In this thesis, experimental evaluation of security vulnerabilities has been performed under DoS attacks for popular personal firewalls from McAfee, Norton and Kaspersky; and for operating systems namely Apple’s Leopard and SnowLeopard, and Microsoft’s Windows XP and Windows 7. Our experimental results show that the firewalls and operating systems behave differently under a given DoS attack. Some of the firewalls crashed under certain DoS attacks especially when they were configured to prevent and block packets belonging to such attacks. Operating systems evaluated in this thesis were also found to have different built-in security capabilities, and some of them even crashed …

An Improved Wideband Vivaldi Antenna Design, Fang Chen

Theses and Dissertations - UTB/UTPA

The objectives of this thesis are to 1) determine how Vivaldi antenna parameters affect the performance and 2) design a Vivaldi antenna with improved overall performance over existing designs. The methodology is to divide the Vivaldi antenna into two parts consisting of microstrip-to-slotline transition and tapered curve part. This has great advantages in finding the relationships between the different antenna parameters and the antenna performance. By combining the methods of improving the impedance- and usable gain bandwidth concluded by the parameter study on the two individual parts, a final Vivaldi antenna design with 10:1 bandwidth is achieved in terms of …

Thermal Analysis Of Railroad Bearings: Effect Of Wheel Heating, Lariza A. Navarro

Theses and Dissertations - UTB/UTPA

Catastrophic bearing failure is a major concern for the railroad industry because it can lead to costly train stoppages. Excessive heat buildup within the bearing is one of the main factors that can warn of impending failure. The work presented in this thesis is motivated by the need to understand the heat transfer paths to the bearing when wheel heating occurs. A series of experiments and finite element analyses were conducted in order to quantify the different heat transfer mechanisms, with emphasis on radiation. The results indicate that the effect of thermal radiation is minimal when the wheel tread temperature …

Gas-Assisted Powder Injection Molding: A Comparison Of Residual Wall Thickness Between Metal Cavity Vs. Sla Cavity And Effect Of Mold Temperature On Residual Wall Thickness, Donghan Kim

Theses and Dissertations - UTB/UTPA

The effects of processing variables on gas penetration depth and Residual Wall Thickness (RWT) in an aluminum (Al) cavity of Gas-Assisted Injection Molding (GAIM) were investigated with Polypropylene (PP) and Stainless Steel Powder Feedstock (SSPF). The selected processing variables were melt temperature, shot size, gas pressure, and gas delay time. By using a Taguchi L9 array, the results were compared with previous work. For PP, there were no significant differences on gas penetration depth. However, the significance of gas delay time was relatively higher in an Al cavity as compared to a Stereolithography (SLA) cavity from previous work with SSPF. …

An Information Technology Suitability Index For Mass Customization, Oscar Leonardo Barrenechea

Theses and Dissertations - UTB/UTPA

In today’s manufacturing world, high competitive markets are pushing companies to find better ways to satisfy their customer’s needs using several Mass Customization (MC) approaches. Consequently, new Information Technologies (IT) have taken a very important role in order to manage the increasing amount of data generated from those customers. The purpose of this thesis is to develop an IT suitability index for MC that would help to identify the critical IT factors to be addressed in order to efficiently support MC. A linear programming regression model was utilized to generate index values. Finally, the results of this model could be …

A Database Server For Next-Generation Scientific Data Management, Mohamed Eltabakh, Walid G. Aref, Ahmed Elmagarmid

Cyber Center Publications

The growth of scientific information and the increasing automation of data collection have made databases integral to many scientific disciplines including life sciences, physics, meteorology, earth and atmospheric sciences, and chemistry. These sciences pose new data management challenges to current database system technologies. This dissertation addresses the following three challenges: (1) Annotation Management: Annotations and provenance information are important metadata that go hand-in-hand with scientific data. Annotating scientific data represents a vital mechanism for scientists to share knowledge and build an interactive and collaborative environment. A major challenge is: How to manage large volumes of annotations, especially at various granularities, …

Improving The Reliability Of Aquatic Biogeochemical Models: Integrating Information And Optimizing Complexity, Cory P. Mcdonald

Dissertations, Master's Theses and Master's Reports - Open

No abstract provided.

An Experimental Study Of Potential Residential And Commercial Applications Of Small-Scale Hybrid Power Systems, Michael Anthony Acosta

Theses and Dissertations - UTB/UTPA

The research presented in this thesis provides an understanding of small-scale hybrid power systems. Experiments were conducted to identify potential applications of renewable energy in residential and commercial applications in the Rio Grande Valley of Texas. Solar and wind energy converted into electric energy was stored in batteries and inverted to power common household and commercial appliances. Several small to medium size hybrid power systems were setup and utilized to conduct numerous tests to study renewable energy prospects and feasibility for various applications. The experimental results obtained indicate that carefully constructed solar power systems can provide people living in isolated …

A Study On Gas Penetration And Fingering Behavior In Injection Molding Of Polymer And Powder Metal Feedstock, Edna I. Orozco

Theses and Dissertations - UTB/UTPA

The effect of processing variables on the level of gas penetration in parts fabricated by gas-assisted injection molding from two different materials was compared. The materials used were polypropylene and stainless steel powder metal/thermoplastic feedstock. Software simulation and physical experiments were conducted. Taguchi analysis was used to reduce the number of experiment trials and to find the optimum processing conditions. Four different variables were changed using nine different combinations. The processing variables are the pressure, the delay time before gas is injected, the temperature of the material injected, and the amount of the material injected. The results showed that the …

The Implementation And Analysis Of Through Wall Radar Systems, Xiaohui Wang

Theses and Dissertations - UTB/UTPA

Through wall radar detecting, locating, imaging and tracking is a topic of current research interest in connection with law enforcement, urban area operations and search and rescue missions. Up to now, three different radar techniques are employed in through wall radar systems, including impulse through wall radar, continuous wave radar and swept frequency radar. In this thesis, we set out to give a comparison of these three kinds of through wall radar systems. First,we studied the challenges caused by the wall in through wall radar systems. Second,we implemented these three kinds of through wall radar system. In each kind of …

Asynchronous Designs On Fpga With Soft Error Tolerance For Security Algorithms, Deepya Reddy Nalubolu

Theses and Dissertations - UTB/UTPA

Asynchronous methodologies, such as Null Convention Logic (NCL), have tremendous potential in implementing digital logic. It is essential to design complex asynchronous circuits using commercial Electronic Design Automation (EDA) tools. The main focus of this thesis is to design NCL circuits using VHDL and implementing them on FPGAs. The major contributions of this thesis include: 1) Developing a methodology of designing NCL circuits with VHDL and applying it successfully to all practical designs in this thesis. 2) As an example, the NCL circuit for DES (Data Encryption Standard) algorithm has been designed and simulated using VHDL and the implementation issues …

Uwb Antennas For Medical Imaging, Khabat Ebnabbasi

Theses and Dissertations - UTB/UTPA

Ultra-Wide Band (UWB) Microwave for imaging applications; especially in the medical field, is a new method to overcome the inherent invasive features of X-ray imaging. In this work a new systematic and detailed design for the Tapered Slot Antenna (TSA) as a UWB antenna in microwave imaging systems for medical applications is presented. Among TSAs, the Vivaldi antenna was selected and the reasons to replace the horn antenna imaging systems are illustrated. In the first chapter the previous designs for microwave imaging and the outline of this work are given, Chapter Two covers the design of the Vivaldi antenna's different …

Droplet Assisted Self-Assembly Of Semiconductor Nanostructures, Kimberly Annosha Sablon

Graduate Theses and Dissertations

There is increasing interest in quantum dot (QD) structures for a plethora of applications, including optoelectronic devices, quantum computing and energy harvesting. While strain driven surface diffusion via stranski-krastanow (SK) method has been commonly used to fabricate these structures, a more recent technique, droplet epitaxy (DE) does not require mismatch strain and is therefore much more flexible in the combination of materials utilized for the formation of QDs.

As reported in this work, a hybrid approach that combines DE and SK techniques for realizing lateral ordering of QDs was explored. First, the droplet formation of various materials was discussed and …

Thermodynamic, Heat Transfer Analysis And Simulation Of A Domestic Size, Double Stage, Lithium Bromide Absorption System, Carlos R. Lima

Theses and Dissertations - UTB/UTPA

The research presented in this thesis provides an investigation into the thermodynamic and heat transfer requirements for a, 3 ton, Water / Lithium-Bromide absorption system. Thermodynamics results for one stage and two stages absorption system are presented. Heat transfer principles provided a design guideline. Flat-plate, solar, water heaters and auxiliary devices using natural gas were analyzed as the main sources for energy inputs into the generator. Experimental data from the solar collector is provided under several configurations. A TRNSYS simulation of the overall absorption, cooling systems and its alternative energy means provided different scenarios where heating loads into the generator …

Development Of Measurement And Modeling Techniques To Quantify Atmospheric Deposition Of Persistent, Bioaccumulative And Toxic Chemicals In The Great Lakes, Mark D. Rowe

Dissertations, Master's Theses and Master's Reports - Open

Measurement and modeling techniques were developed to improve over-water gaseous air-water exchange measurements for persistent bioaccumulative and toxic chemicals (PBTs). Analytical methods were applied to atmospheric measurements of hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs). Additionally, the sampling and analytical methods are well suited to study semivolatile organic compounds (SOCs) in air with applications related to secondary organic aerosol formation, urban, and indoor air quality.

A novel gas-phase cleanup method is described for use with thermal desorption methods for analysis of atmospheric SOCs using multicapillary denuders. The cleanup selectively removed hydrogen-bonding chemicals from samples, including much of …

Long-Range Pollution Transport: Trans-Atlantic Mechanisms And Lagrangian Modeling Methods, Robert Christopher Owen

Dissertations, Master's Theses and Master's Reports - Open

Over the past several decades, it has become apparent that anthropogenic activities have resulted in the large-scale enhancement of the levels of many trace gases throughout the troposphere. More recently, attention has been given to the transport pathway taken by these emissions as they are dispersed throughout the atmosphere. The transport pathway determines the physical characteristics of emissions plumes and therefore plays an important role in the chemical transformations that can occur downwind of source regions. For example, the production of ozone (O₃) is strongly dependent upon the transport its precursors undergo. O₃ can initially be formed …

Numerical Simulation Of Thermo-Elasticity, Inelasticity And Rupture Inmembrane Theory, Michael Taylor

Mechanical Engineering

Two distinct two-dimensional theories for the modeling of thin elastic bodies are developed. These are demonstrated through numerical simulation of various types of membrane deformation. The work includes a continuum thermomechanics-based theory for wrinkled thin films. The theory takes into account single-layer sheets as well as composite membranes made of multiple lamina. The resulting model is applied to the study of entropic elastic elastomers as well as Mylar/aluminum composite films. The latter has direct application in the area of solar sails. Several equilibrium deformations are illustrated numerically by applying the theory of dynamic relaxation to a finite difference discretization based …

Nanoengineered Templates For Controlled Delivery Of Bioactive Compounds, Nalinkanth Ghone Veerabadran

Doctoral Dissertations

The significance of any drugs, therapeutic proteins, or any bioactive compounds, is based not only on their effects on diseases but also on how specifically, how readily, how controllable and how prolonged their effects on the disease without having any side effects. Thus the techniques involved in the drug encapsulation and its controlled release for a longer duration of time form one of the important processes of drug reformulation. In recent years nanoparticles have created overwhelming attention for delivering drugs by nanoencapsulation. The smaller size of nanoparticles has longer circulation time and higher cellular uptake when compared with larger size …

Planning And Adaptation Measures For Urban Slum Communities In West Africa : Stochastic Rainfall Modeling Applied To Domestic Rainwater Harvesting And Climate Change Adaptation, Joshua R. Cowden

Dissertations, Master's Theses and Master's Reports - Open

Over half of the world’s population is living in urban settlements, and most urban growth is occurring in developing countries. These countries’ economies are often unable to accommodate these rural-urban immigrations, resulting in millions of people settling in insecure communities known as urban slums. Current efforts to prevent urban slums include UN-HABITAT strategies to upgrade slums and stimulate urban/regional development. Urban metabolism analysis, which studies material and energy flows/stocks through urban processes, help decision-makers better understand their urban system. Nine lessons from past urban metabolism studies are presented to assist in finding answers on how to best solve urban slum …

A Finite Element Study Of Piezoelectric Thin Films On Substrates, Bo Liu

Theses and Dissertations

The overall goal of this work has been mainly to advance the understanding of the degradation in the response of piezoelectric thin films after they are deposited on substrates. To have better understanding of the difference in the response between free standing piezoelectric films and those deposited on a substrate, we calculated the normalized "effective" piezoelectric coefficients for BT/MgO, PZT/STO and ZnO/STO respectively. We also studied the impact on the effective coefficients due to the components of the bulk material's piezoelectric coefficients. After studying the clamping effects of the substrate, lattice mismatch, stiffness of the films and the substrates, we …

Drug Loading And Release From Polypeptide Multilayer Nanofilms, Yang Zhong

Doctoral Dissertations

Polypeptides, linear macromolecules, are formed from amino acid residues by linkage of peptide bonds. Proteins are polypeptides too, with more complex conformations contributing to specific functionalities. Disulfide bonds are very important to maintain the structure and functions of proteins, which will form between two cysteine (Cys) residues under oxidizing circumstance.

Cys containing polypeptides are designed and synthesized by F-moc (9-Fluorenylmethyloxycarbonyl) chemistry. The number and position of Cys residues can be controlled by amino acid sequences design and following peptide synthesis, which is important to gain insights on the nature of polyelectrolyte multilayer film assembly and stability.

Both commercial and designed …

Nitrogen Oxides In The North Atlantic Troposphere: Impacts Of Boreal Wildfire And Anthropogenic Emissions, Maria Val Martin

Dissertations, Master's Theses and Master's Reports - Open

Nitrogen oxides play a crucial role in the budget of tropospheric ozone (O sub(3)) and the formation of the hydroxyl radical. Anthropogenic activities and boreal wildfires are large sources of emissions in the atmosphere. However, the influence of the transport of these emissions on nitrogen oxides and O sub(3) levels at hemispheric scales is not well understood, in particular due to a lack of nitrogen oxides measurements in remote regions. In order to address these deficiencies, measurements of NO, NO sub(2) and NO sub(y) (total reactive nitrogen oxides) were made in the lower free troposphere (FT) over the central North …